1. Field of the Invention
The present invention relates to a process for preparing surfactant compositions and, more particularly, to a method for producing a surfactant composition comprising a soap and alkoxylated mono- and diglycerides as moisturizing agents.
2. Description of the Prior Art
Recently, the cosmetic industry has placed greater emphasis on natural ingredients with proven mildness. In particular, ethoxylated (alkoxylated) mono-and diglycerides are known for their mildness and have been recently demonstrated to be effective moisturizing agents. Not only do these ethoxylated glycerides appear to have excellent moisturizing and mildness characteristics, they also possess surfactant properties; e.g., they are non-ionic surfactants. Accordingly, while theoretically they could be incorporated into a soap composition--.g., a skin cleanser--to impart moisturizing characteristics, it would clearly be desirable to have a process wherein there was produced, in a single reaction, a skin cleanser containing both soap and the ethoxylated glycerides.
It is known that hydroxylated, ethoxylated triglycerides of fatty acids--e.g., ethoxylated castor oil-can be partially saponified to form a polyoxyethylene fatty acid alkali soap. Thus, in U.S. Pat. No. 3,663,583, there is described a process for producing a saponified ethoxylated triglyceride of ricinoleic acid. Ricinoleic acid is a hydroxy fatty acid having the structure: ##STR2##
which produces a triglyceride having the following structure: ##STR3##
wherein R stands for the fatty portion of the ricinoleic acid--i.e., the portion containing the hydroxyl group and the olefinic linkage. In the process described in U.S. Pat. No. 3,663,583, conventional ethoxylation catalysts such as NaOH and KOH are used to effect the ethoxylation of the hydroxytriglyceride. As would be expected, this results in ethoxylating the hydroxy group of the castor oil such that subsequent saponification cleaves the triglyceride portion of the molecule, resulting in the formation of the polyoxyethylene ricinoleate soap. Thus, the process of U.S. Pat. No. 3,663,583 does not produce a surfactant composition that, in addition to having a soap, also contains mono-and diethoxylated glycerides to act as moisturizing agents.
It is known from U.S. Pat. No. 5,386,045 that alkoxylated triglycerides or triesters having the formula: ##STR4##
wherein n is from 2 to 4, p.sub.1, p.sub.2, and p.sub.3 are each from about 1 to about 50, preferably 1 to 15, and R is an organic radical containing from about 6 to about 30 carbon atoms, preferably a linear or branched chain alky group, can be prepared starting by reacting an alkylene oxide, e.g., ethylene oxide, with a triglyceride having the formula: ##STR5##
As disclosed in U.S. Pat. No. 5,386,045, the reaction is generally conducted at a temperature of from about 80.degree. C. to about 200.degree. C. and a pressure that can range from subambient up to about 100 psi or higher. A catalytic effective amount of a calcium catalyst is employed in the reaction. The catalyst is selected from the group consisting of (a) Calcium Catalyst A, formed by reacting a reactant mixture comprising an alkoxylated alcohol mixture containing compounds having the general formula: EQU R.sub.1 --O--(C.sub.n H.sub.2n O).sub.p --H
wherein R.sub.1 is an organic radical containing from about 1 to about 30 carbon atoms, preferably a linear or branched chain alkyl group, and p is from 1 to 50, preferably 1 to 15, a calcium-containing compound that is at least partially dispersible in said alkoxylated alcohol, an inorganic acid compound, and a metal alkoxylate of an acidic metal, the calcium-containing compound and the alkoxylated alcohol mixture being mixed prior to addition of the metal alkoxide, the reactant mixture being heated to a temperature and for a time sufficient to effect at least a partial exchange reaction between the alkoxide groups of said metal alkoxide and the hydroxyl groups of the alkoxylated alcohol; (b) Calcium Catalyst B, formed by solubilizing, at least partially, a calcium-containing compound with an activator having the formula: EQU Z.sub.a --X--Q--Y--Z'.sub.b
wherein X and Y are the same or different electro-negative, hetero-atoms selected from the group consisting of oxygen, nitrogen, sulfur, and phosphorus, a and b are the same or different integers satisfying the valency requirements of X and Y, Q is an organic radical that is electro-positive or essentially neutral relative to X and/or Y and Z and Z' are the same or different and are either hydrogen or an organic radical that does not prevent said solubilizing; and (c) mixtures of Calcium Catalyst A and Calcium Catalyst B.
In U.S. Pat. No. 6,020,509, there is disclosed a process for producing a surfactant composition containing a conventional soap in admixture with moisturizing agents. In the process disclosed in U.S. Pat. No. 6,020,509, incorporated herein by reference for all purposes, an alkoxylated triglyceride is partially saponified with an alkali metal hydroxide, the process being conducted in the presence of a minimal amount of free water. While the process disclosed in U.S. Pat. No. 6,020,509 produces the desired product, it suffers from the infirmity that the time to saponify the triglyceride is unacceptably long.